Business, Basis of Presentation and Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Apr. 30, 2020
Buildings
Property and equipment
Depreciation expense for property and equipment (as a percent)	4.00%
Buildings | Minimum
Property and equipment
Estimated useful life	25 years
Buildings | Maximum
Property and equipment
Estimated useful life	39 years
Furniture, fixtures and automobiles | Minimum
Property and equipment
Estimated useful life	3 years
Furniture, fixtures and automobiles | Maximum
Property and equipment
Estimated useful life	5 years
Warehouse and delivery equipment | Minimum
Property and equipment
Estimated useful life	4 years
Warehouse and delivery equipment | Maximum
Property and equipment
Estimated useful life	10 years
Vehicles and trucks | Minimum
Property and equipment
Depreciation expense for property and equipment (as a percent)	30.00%
Vehicles and trucks | Maximum
Property and equipment
Depreciation expense for property and equipment (as a percent)	40.00%
Furniture and fixtures | Minimum
Property and equipment
Depreciation expense for property and equipment (as a percent)	8.00%
Furniture and fixtures | Maximum
Property and equipment
Depreciation expense for property and equipment (as a percent)	20.00%
Machinery and equipment
Property and equipment
Depreciation expense for property and equipment (as a percent)	30.00%